Field of the Invention
The present invention relates to a lens apparatus, and particularly to a lens apparatus that drives a movable optical member by a driver and an image pickup apparatus including the same.
Description of the Related Art
A lens apparatus has difficulty in driving an optical member to a target position with high accuracy in some situations due to control factors such as an operation torque and a control gain and environmental factors such as an orientation difference of the lens apparatus and an ambient temperature. To deal with these situations, there have heretofore been proposed an apparatus that stores a convergence correction value and an apparatus that performs drive control with high accuracy using a special driver. For example, Japanese Patent Application Laid-Open No. 2004-192200 discloses a motor control apparatus that, when the power is turned on, drives an optical member, detects a positional deviation toward convergence on a target position, and evaluates the convergence based on the positional deviation. In addition, Japanese Patent Application Laid-Open No. 2003-66312 discloses a lens apparatus that includes two actuators as drivers, and stops an optical member at the focus point with high accuracy using a shape changing actuator capable of fine driving around the focus point.
However, the apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-192200 cannot deal with a change in the shooting conditions, because the positional deviation used to evaluate the convergence of a stop position on a target position is dependent only on the orientation difference and the temperature condition at the moment of the calculation of the evaluation value In the meantime, the apparatus disclosed in Japanese Patent Application Laid-Open No. 2003-66312 needs to be provided with two actuators, which might be a factor that imposes constraints on the driver of the lens apparatus.